Down syndrome is a genetic condition that results when there is an extra copy of a specific chromosome, chromosome 21.

It is not an illness but a term that describes the features resulting from this change.

The extra chromosome can affect the physical features, intellect, and overall development of an individual.

It also increases the likelihood of some health problems.

Down syndrome happens when there is an extra copy of genetic material on all or part of the 21st chromosome.

Every cell in the body contains genes that are grouped along chromosomes in the cell's nucleus. There are normally 46 chromosomes in each cell, 23 inherited from the mother and 23 from the father.

When some or all of a person's cells have an extra full, or partial, copy of chromosome 21, the result is Down syndrome.

Down syndrome is not a disease so it may be more appropriate to refer to features or characteristics, rather than symptoms.

People with Down syndrome often have distinct physical features, unique health issues, and variability in cognitive development.

Physical characteristics include 

• eyes that have an upward slant, oblique fissures, epicanthic skin folds on the inner corner, and white spots on the iris
• low muscle tone
• small stature and short neck
• flat nasal bridge
• single, deep creases across the center of the palm
• protruding tongue
• large space between large and second toe
• a single flexion furrow of the fifth finger

Down syndrome is a genetic condition that results when there is an extra copy of a specific chromosome, chromosome 21.

It is not an illness but a term that describes the features resulting from this change.

The extra chromosome can affect the physical features, intellect, and overall development of an individual.

It also increases the likelihood of some health problems.

Down syndrome happens when there is an extra copy of genetic material on all or part of the 21st chromosome.

Every cell in the body contains genes that are grouped along chromosomes in the cell's nucleus. There are normally 46 chromosomes in each cell, 23 inherited from the mother and 23 from the father.

When some or all of a person's cells have an extra full, or partial, copy of chromosome 21, the result is Down syndrome.

Down syndrome is not a disease so it may be more appropriate to refer to features or characteristics, rather than symptoms.

People with Down syndrome often have distinct physical features, unique health issues, and variability in cognitive development.

Physical characteristics include 

• eyes that have an upward slant, oblique fissures, epicanthic skin folds on the inner corner, and white spots on the iris
• low muscle tone
• small stature and short neck
• flat nasal bridge
• single, deep creases across the center of the palm
• protruding tongue
• large space between large and second toe
• a single flexion furrow of the fifth finger